Hydrogenation of lube oils



United States Patent 3,425,932 HYDROGENATION OF LUBE OILS Harland J.Surrena, Media, Aubrey M. Kirby, Jr., Swarthmore, and Henry E. Reif,Bryn Mawr, Pa., assignors to Sun Oil Company, Philadelphia, Pa., acorporation of New Jersey No Drawing. Filed Oct. 21, 1966, Ser. No.588,324

US. Cl. 208143 9 Claims Int. Cl. C10g 23/00 ABSTRACT OF THE DISCLOSURE Aprocess of hydrogenating lube oil fractions having a viscosity in therange of about 50* SUS at 100 F. and about 240 molecular weight at about6000 SUS at 100 F. and about 500 molecular weight wherein the higherviscosity and higher molecular weight materials are enhanced as to theUV absorptivity at 260 III/L. Specifically, the heavier fractionsenhanced in UV are those above about 1000 SUS at 100 F. and above about360 molecular weight by blending same with a lower viscosity and lowermolecular weight material having a viscosity in the range of about 50SUS at 100 F. and about 240 molecular weight to below about 1000 SUS at100 F. and below about 360 molecular weight, hydrogenating same over asulfactive hydrogenation catalyst at a temperature in the range of about450 to 750 F. and a hydrogen partial pressure of about 100 to 10,000p.s.i.g. but preferably a temperature in the range of about 475 to 625F. and a pressure in the range of about 500 to 2000 p.s.i.g., and thenseparating the two blended oils.

In brief, this application pertains to improvements in hydrogenation oflubricating oils. More specifically, this invention relates to the useof combined crude fractions of widely different viscosities or a lubefraction containing components which cumulatively represent a relativelybroad spectrum of viscosities in hydrogenation operations wherebyimprovements in the lubricating oil are obtained, and particularly inregard to UV absorptivity of the heavier fractions thereof.

Certain lube fractions have been found suitable for many uses for whichother lube fractions are not suitable or at least not preferred.Accordingly, some properties thereof are more critical when a particularfraction and a particular use are contemplated.

Traditionally, a crude is fractionated into a plurality of lubricatingoil distillates of varying boiling points and viscosity for theparticular end use or end uses contemplated. Preparatory to suchdistillation of wide fractions, however, the crudes are appropriatelytreated in accordance to their type and characteristics as determined bysource of same.

In the case of say naphthenic crudes, for example, they are treated withan alkaline material to remove naphthenic acids which are always foundpresent in such crudes in significant amounts. lllustratively, thenaphthenic acids are removed according to the procedures of U .8.Patents 2,770,580 and 2,966,456. Following the distillation, the variousfractions are generally hydrogenated to desulfurize, to remove some ofthe nitrogen present and to selectively hydrogenate the lube oil itselfwhereby its properties are enhanced.

Paraffinic base crudes receive a different treatment, but conventionalfor that type such as deasphalting, dewaxing, etc., prior to thehydrogenation. However, the lube fractions once obtained in conventionalfashion are hydrogenated for substantially the same reasons and atsubstantially the same general conditions as indicated for thenaphthenic crudes. One specific important property which thehydrogenation is intended to enhance in certain cases, and particularlyin rubber oils, is the ultraviolet absorptivity and especially at 260 mSince these various distillate fractions are prepared with different enduses in mind, the hydrogenations have quite naturally been carried outon each fraction.

The foregoing statement is especially true in the case of the naphthenicbase lubricating oils, because they are routinely fractionated early inprocessing into the respective fractions and generally in the causticdistillation stage. For this reason, the present inventive concept ofcombinging certain of the fractions for purposes of the hydrogenationconstitutes a particularly unobvious, surprising and unexpectedprocedure. It is equally unobvious and an unexpected procedure in allcases where the lubricating oil has been fractionated into respectivefractions theretofore. 'It would appear on the surface to be a backwardstep.

To the accomplishment of the foregoing and related ends, a blend ofpartially refined lube stock with properties varying in the range fromabout 200 SUS viscosity at F. and an average molecular weight of about300 to about 1000 SUS viscosity at 100 F. and an average molecularweight of about 3610 and comprised of a mixture of components havingviscosities which for simplicity here is broadly stated merely to be inthe range of about 50 to about 6000 SUS at 100 F. and of about 240 to500 average molecular weight respectively, is passed over ahydrogenation catalyst at a temperature within the approximate range of450 to about 750 F., at a pressure within the aproximate range from 100p.s.i.g. to about 4000 p.s.i.g., in the presence of hydrogen.

It has been mentioned heretofore that in the practice of this invention,the hydrocarbon feed components that are blended are to have a viscosityvarying in the range of about 50 to about 6000 SUS at 100 F. (or 32 to200 SUS at 210 F.), and of about 240 to 500 average molecular weightrespectively; however, this is not entirely ac curate without furtherqualification. While the individual components or fractions that blendto form the feed are to fall generally within the foregoing broad range,it is essential that there be substantial amounts of material presentwhich, as isolated fractions, have a SUS viscosity of at least about1000 SUS at 100 F. and about 360 average molecular weight and belowabout 6000 SUS at 100 F. and below about 500 average molecular weightrespectively. This is so because only the lube fractions above about1000 SUS at 100 F. in viscosity and 360 average molecular weight havebeen found to be improved by this invention, and accordingly, in orderto fully utilize the present invention there must be some of thismaterial present. The more important benefits of the invention areobtained only under such condition. Other components do not experienceany significant disadvantages from such procedure, however, theimportant benefits are not attained in such cases and, accordingly, suchtechnique provides no incentive in utilizing feeds of lower viscosityexclusively in such situations. On the other hand, at the same time thatsome components of a viscosity above 1000 SUS at 100 F. and 360 averagemolecular weight must be employed in order to obtain the importantenhanced beneficiation in properties thereof (as compared to separatehydrogenation of same), it is equally essential that some materialhaving a viscosity below about 1000 SUS at 100 F. and 360 averagemolecular weight be present to affect the improvement in UV absorptivityof said relatively heavier lube oil fraction, and preferably having aviscosity of about 500 SUS at 100 F. down to about 50 SUS at 100 F. andabout 3 5 down to about 240 average molecular weight respectively.

The individual components of fractions that are blended or otherwisecurnmulatively comprise the charge to the hydrogenation zone mustpossess viscosity characteristics from each of the foregoing ranges, inaddition to the most important requirement of the charge stock, that themixture or blend have a composite viscosity of about 200 SUS viscosityat 100 F. and about 300 average molecular weight to 1000 SUS viscosityat 100 F. and about 360 average molecular weight as previously setforth, but preferably has viscosity of about 250 SUS at 100 F. and about325 average molecular weight to about 500 SUS at 100 F. and about 345average molecular weight.

The preferred manner of operation is to operate in liquid phase and topass the charge stock and hydrogen over the hydrogenation catalyst indownward co-current fashion according to the technique which isfrequently referred to as the trickle-phase operation, although onoccasion it may be preferred to feed the hydrogen in counter-currentfashion.

The hydrogenation catalysts which are suitable are Well known in the artand examples are copper, zinc, magnesium, tin, vanadium, tungsten,chromium, molybdenum, manganese, cobalt, iron, nickel, platinum, etc. ortheir oxides of sulfides or such or mixtures of such metals or theiroxides or sulfides. Any of the well-known catalyst carriers may beemployed as such carriers as activated carbon, alumina, bauxite,charcoal, clay, kieselguhr, magnesia, pumice, silica, silica-aluminacompositions, etc. The preferred catalyst are combinations of cobalt andmolybdenum and nickel and molybdenum. Said combinations having beenpresulfided according to well-known techniques so that they are used inthe form of the sulfides on alumina as a carrier.

Although the temperature range broadly suitable is 450 to 750 F.,preferably it is within the range of about 475 to 625 F. and still morepreferably, the temperature is about 575 to 625 F.

The hydrogen partial pressure range broadly suitable is about 100 to4000 p.s.i.g., but preferably, the pressure employed is about 500 to2000 p.s.i.g., and more preferably, 1000 to 1500 p.s.i.g.

The hydrogen employed is preferably a hydrogen stream containing atleast about 70 percent hydrogen; however, any hydrogen-rich refinerystream may be em ployed. Generally, the hydrogen stream is employed inan amount varying from about to 1000 s.c.f./barrel of lubricating oil,and more preferably, about 50 to 300 s.c.f. on the same basis. The spacerates may vary over a wide range depending on the design of the reactorand the residence time desired, but generally, such space rates willvary between about 0.25 to volumes of liquid charge per volume ofcatalyst bed per hour. Of course, in regard to the space rates, anyrecycle of material is to be considered in determining the foregoingfigure. Gas recycle may be employed for example, as set forth in US.2,918,425 or liquid may be recycled either internally (i.e., before anypurification) or according to conventional recycle techniques ofrecovering unconverted partially converted or reacted material andreturning same to the reactor.

Following the hydrogenation, the oil is then fractionated into aplurality of lubricating oil distillates of varying boiling points andviscosity. Generally, the propertie are for all practical purposessubstantially the same as those the same fractions have if hydrogenatedseparately. There is at least one important exception, however, and thisinvolves an improved UV absorptivity at 260 mg of the fraction or thosefractions with a viscosity above about 1000 SUS at 100 F. and about 360average molecular weight. Following this fractionation, the fractionsmay be further treated according to the needs of the particular end useintended. For example, they may be extracted with solvents such asfurfural, methyl ethyl ketone, etc. They may be instead or in additiontreated with clays and/or sulfuric acid.

To facilitate the understanding of the invention, certain details andillustrative embodiments will now be set forth; however, of course, itis to be fully understood and appreciated that the invention is notlimited to the specific conditions or details set forth in theseexamples, since the process is capable of many modifications andvariations and conditions, such modifications and variations beingaided, suggested or indicated by the discussion of the process .as foundherein and the discussions of the trends of the effect of variousfactors.

EXAMPLE I A Grade A crude mix (a naphthenic base crude) of about 0.89viscosity-gravity constant was caustic distilled according to theprocedure of US Patent 2,770,580. A blend of the fractions were preparedwith a viscosity of about 340 at F. and about 47 at 210 F. This blendand hydrogen were continuously fed to a conventional trickle-phasehydrogenation reactor in conventional fashion and was hydrogenated in acontinuous operation over a presulfided nickel-molybdenum on aluminacatalyst at a pressure of about 1000 p.s.i.g and at temperature of about600 F. Fresh feed with a UV absorptivity of about 11.2 was charged at arate of about 0.5 volume of feed per volume of catalyst per hour andliquid product was recycled at a rate to provide a total liquid spacerate of about 4.0 volumes of liquid per volume of catalyst per hour. Amake-up stream of 100 percent hydrogen at a rate of approximately 235s.c.f./bbl. was required. The hydrogenated product was fractionated toprovide three separate fractions (see the table below, left-hand side).The heaviest fraction with a viscosity of about 2800 SUS at 100 F. andan average molecular weight of about 396 exhibited the most improvementin UV as compared to separate hydrogenation. This fraction had a UVabsorptivity of 4.1.

When this same fraction (i.e., of comparable viscosity, about 2800 SUSat 100 F., and about the same average molecular weight, 381) washydrogenated separately directly from the caustic distillation at thesame conditions, it had a UV absorptivity of 4.9, although the otherproperties were substantially the same as when blended beforehydrogenation in accordance with the foregoing run. This is more than 16percent improvement in UV absorptivity. The other fractions, however,were not found to be sacrificial to the improvement in UV obtained ofthe higher molecular weight material when the feeds were blended andhydrogenated together as shown by the data below.

Combined feed stream Separate feed stream Having now described theinvention, many ramifications and modified embodiments Will readilyoccur to those skilled in the art. Insofar as such variations do notdepart from the spirit and scope of the invention described in thisapplication, they are intended to be embraced by the appended claims intheir broadest constructlon.

We claim:

1. In a process of hydrogenating lubricating oils having propertiesvarying in the range from about 50 SUS at 100 F. and about 240 molecularweight to about 6000 SUS at 100 F. and about 500 molecular weight withhydrogen over a hydrogenation catalyst, the improvement which comprisescharging as feed to said hydrogenation zone a lubricating oil distillatehaving a composite viscosity in the range of about 200 SUS at 100 F. andabout 300 molecular weight to about 1000 SUS at 100 F. and about 360molecular weight with the further provision that said compositeviscosity is obtained as a mixture of at least two distillate fractionswherein at least one of said fractions has a viscosity in the range ofabout 50 SUS at 100 F. and about 240 molecular weight to below about1000 SUS at 100 F. and below about 360 molecular weight and at least oneof said fractions has a viscosity of above about 1000 SUS at 100 F. andabove about 360 molecular weight up to about 6000 SUS at 100 F. andabout 500 molecular weight, and separating said heavier distillatefraction having a viscosity above about 1000 SUS at 100 F. and aboveabout 360 molecular weight from said lower viscosity and lower molecularweight fraction.

2. A process according to claim 1 wherein said hydrogenation withhydrogen over a hydrogenation catalyst is conducted at a temperaturewithin the range of about 450 to 750 F. and at a pressure within therange of about 100 p.s.i.g. to about 4000 p.s.i.g.

3. A process according to claim 2 wherein said hydrogen employed is arefinery hydrogen stream of at least about 70 percent hydrogen.

4. The process according to claim 2 wherein the space rates employedvary from about 0.25 to 20 volumes of liquid oil charge per volume ofcatalyst bed per hour and about to 1000 standard cubic feed of hydrogenper barrel of liquid oil charge.

5. The process according to claim 4 wherein the oil charge has acomposite viscosity in the range of about 250 SUS at 100 F. and about325 molecular weight to about 500 SUS at 100 F. and about 345 molecularweight.

6. The process according to claim 5 wherein the hydrogenation catalystemployed is a presulfided nickeltungsten on alumina, nickel-molybdenumon alumina or cobaltmolybdenum on alumina catalyst.

7. The process according to claim 6 wherein the hydrogenationtemperature employed is in the range of about 575 to 625 F.

8. The process according to claim 7 wherein the hydrogen partialpressure at which the hydrogenation is carried out is in the range ofabout 500 to 2000 p.s.i.g.

9. The process according to claim 8 wherein said hydrogenation catalystis a nickel-molybdenum on alumina catalyst obtained by sulfiding anickel oxide-molybdenum oxide mixture on alumina wherein nickel oxide ispresent in an amount equal to about 3 percent and molybdenum oxide ispresent in an amount equal to about percent, sodium oxide is present inabout 0.02 percent by weight and the remainder is alumina.

References Cited UNITED STATES PATENTS DELBERT E. GANTZ, PrimaryExaminer.

HERBERT LEVINE, Assistant Examiner.

US. Cl. X.R. 208-18, 144

